Most heads and tripods connect to one another with 3/8" threads, but some tripod legs will have a 1/4" thread instead- this bushing will solve that problem by converting a 1/4" external thread to a 3/8". Similarly, some older cameras are designed with a 3/8" inner thread for mounting to tripods. This small metal bushing screws into that 3/8" inner thread and turns it into a 1/4" thread, so you can mount your camera to a standard tripod head. A good quality new part made in Germany.

Image is for illustrative purposes and the actual item may not be identical.